How to show battery health at the point of sale

For many buyers of a used electric car, the first serious question is about the battery. It is the most expensive part of the car, it ages in ways the odometer does not record, and a test drive says very little about it. This guide is for dealers in the UK and the EU who want to answer that question with something the buyer can check, on the forecourt and in online listings.

Why buyers ask

A buyer may know that batteries lose capacity over time, but has no way to tell how much this one has lost. Neither the dashboard range nor the charge gauge tells them. So the buyer takes your word for it, discounts the price for the risk, or keeps looking.

The figure that answers the question is State of Health (SoH): the usable energy or capacity of the battery today, as a percentage of what the same battery variant offered when new. Buyer guides, ours included, tell buyers to ask for a recent certificate and to verify it themselves. In France, the government and part of the industry have agreed to show it, as described below.

What to show on the forecourt and in listings

Four details do most of the work. Show them together, in the same place, on every car.

The SoH and the grade. Give the SoH as it appears on the certificate, with its uncertainty band, and put the grade next to it. The grade comes from the SoH alone, on the same bands for every make (A from 85%, B from 70%, C from 55%, D from 40%, F below 40%), so a buyer comparing two cars of different makes is comparing like with like.

The certificate ID or QR code. This is what turns your claim into something the buyer checks. The QR code opens the certificate's live record at battgrade.com/verify, and the page checks the digital signature every time it opens. The ID does the same for anyone who types it in.

The test date and the validity. A certificate records the battery on the day of the test and is valid for 6 months from the day it is issued. Show both dates, so nobody has to guess whether the reading is recent.

Any flags. If the certificate records a check result such as uneven cells, show it and explain it. A buyer who finds a flag you did not mention will trust the rest of your listing less.

On the forecourt, all of this fits on the windscreen card: the SoH with its band, the grade, the test date, the expiry date and the QR code, printed large enough to scan through the glass. In an online listing, put the same details in the description and link to the certificate's verification page rather than posting a photo of the PDF. A photo can be edited. The record behind the QR code cannot be changed without the page showing it.

On the public verification page the VIN is partly hidden and the customer's details do not appear, so the link is safe to publish.

How a verifiable certificate helps the conversation

We have not measured whether cars with a certificate sell faster or for more, and we will not quote a figure we do not have. What a verifiable certificate changes is the conversation itself.

Without one, the battery is a matter of trust: you say it is fine, and the buyer wonders how you know. With one, you can point to a number with a method behind it and let the buyer check it on their own phone. Your team runs the test, but the result is calculated and signed by BattGrade's server from the raw data read from the car, so nobody at the dealership can type it in or change it, and the certificate names who ran the test.

It also helps with the cars whose batteries are not perfect. A car with a C grade and a clear certificate is a car you can price honestly and explain, rather than one whose battery the buyer finds out about later. Showing the weaker results alongside the strong ones is what makes the strong ones believable.

Your claim about the battery becomes something the buyer checks on their own phone.

Practical steps

Test at intake. Read the battery when the car arrives, before you price, photograph or list it. You need a phone with the BattGrade app, a supported Bluetooth OBD2 adapter and the car awake, with the ignition on or in READY mode depending on the model. The test takes a few minutes, and the app only sends read-only requests, so nothing is written to the car. The coverage page lists the models the app can read today and the adapter each one needs.

Put the QR code on the windscreen card and in the listing. Use the same certificate everywhere, so the forecourt, the website and the paperwork tell the same story.

Re-test after 6 months. A certificate shows as expired after 6 months. If a car is still in stock by then, test it again and replace the card and the link with the new certificate. Re-test sooner after any work on the high voltage system.

Make it routine. Decide who in the team runs the tests, test every electric car the same way, and keep each certificate with the car's file. How it works shows every step, and every field of a certificate, on an example.

What not to claim

A battery certificate is persuasive because it is precise. Keep your own claims just as precise.

Do not present SoH as range. SoH compares the battery with the same battery when new. The range a buyer gets also depends on the car, the weather and how it is driven.

Do not call the certificate a warranty or a full inspection. It records the battery on the day of the test, with the checks the car's data allows, not every possible fault and not the battery's future condition.

Do not call it official. BattGrade is a private company, not a public authority and not an accredited test lab. Describe it as a battery test run by your team, with the result calculated and signed by BattGrade's server.

Do not say a car is battery passport compliant because it has a certificate. A third-party battery certificate is not a battery passport.

Do not round up, leave out the band or show an expired certificate as current. If the reading is old, test again.

The regulatory context

In the EU, the Battery Regulation introduces a digital battery passport. From 18 February 2027, each electric vehicle battery placed on the market or put into service must have one, and the economic operator that places the battery on the market is responsible for keeping its information accurate, complete and up to date (Regulation (EU) 2023/1542, Article 77). It is not a record a dealer creates for a used car, and a third-party battery certificate does not make anyone compliant with it.

The same regulation gives anyone who has legally bought a battery, or a third party acting for them, read-only access to the battery management system data used to estimate its state of health, for purposes that include evaluating its residual value (Article 14). A BattGrade test reads the battery management system in the same read-only way.

In France, Monique Barbut, the minister for ecological transition, launched the Pacte de confiance pour les véhicules électriques d'occasion, a trust pact for used electric vehicles, in Rambouillet on 4 September 2026 (ministry announcement). It was signed with Aramis Group, CSIAM, Mobilians, PFA (Plateforme automobile), Renault and Stellantis. In the minister's words, used electric cars sold through dealerships are to display the state of health of their battery (the minister's statement).

Rules differ by country and are still changing, so check what applies where you sell.

Getting started

BattGrade is in early access: the Android app is in testing and the iPhone version comes next. To show battery health on your own stock, see BattGrade for dealers or get early access.